Poly s, optically active

Isocyanide Polymers Bulky isocyanides give polymers having a 4 1 helical conformation (115) [154]. An optically active polyisocyanide was first obtained by chromatographic resolution of poly(f-butyl isocyanide) (poly-116) using optically active poly((S)-sec-butyl isocyanide) as a stationary phase and the polymer showing positive rotation was found to possess an M-helical conformation on the basis of CD spectral analysis [155,156]. Polymerization of bulky isocyanides with chiral catalysts also leads to optically active polymers. 

The H and 13C NMR spectra of azo compounds incorporated into monomers and polymers have been measured.67-73 Chiral methacrylic polymers containing azobenzene chromophore,67,68 epoxy-based polymers functionalized with tricyanivinylphenylazo chromophores,69 4-vinylazobenzene and homo- and copolymers,70 microstructure of trans-4-acrylooyloxyazo-benzene/methyl methacrylate copolymers,71 optically active poly[(S)-4-(2-methacryloyloxypropanoyloxy)azobenzene]72 and polyetherurethane pendant with azo dye by TV-substitution73 have been studied. 

Optically active poly [(S )-(+)-2-methylbutylisocyanate] (XlXa) [47] and poly [(c/-j3-phenylpropylisocyanate)] (XlXb) [48] were obtained by anionic polymerization of the corresponding isocyanate in presence of sodium cyanide as catalyst. When the isocyanate... 

An interesting aspect of the benzofuran cationic polymerization was uncovered by Natta, Farina, Peraldo and Bressan who reported in 196160,61 that an asymmetric synthesis of an optically active poly(benzofuran) could be achieved by using AlCl2Et coupled with (-)j3-phenylalanine, (+)camphorsulphonic acid or with (-)brucine. The optical activity was definitely due to the asymmetric carbon atoms in the polymer chain, indicating that at least some of the polymer s macromolecules possessed a di-isotactic structure, v/ z.62 ... 

Figure 4.2 shows the UV absorption spectra of four optically active poly(dialkylsilane)s bearing different chiral side groups in THF at 30°C.32a It is evident that as the value of a increases from 0.59 to 1.25, the UV... 

In this section, we comprehensively focused on the controlled synthesis, chiroptical characterization, and manipulation of optically active poly(dialkyl-silane)s. Although many artificial polymers adopting preferential screw sense... 

Since for the diarylpolysilanes, as for all polysilanes, the main chain is chromophoric due to the electronic transition between the delocalized silicon a and a orbitals, the electronic spectroscopies of CD, UV-Vis, and FL are particularly powerful probes of the structures of these materials. The magnitude of dimensionless quantity, gabs, is perhaps the most useful in comparing the CD spectra of optically active poly(diarylsilane)s. 

The hydrocarbon 25 has been partially resolved by asymmetric complexation with Newman s reagent [TAPA ( )-a(2,4,5,7-tetranitro-9-fluorenylideneaminooxy)prop-ionic acid] thereby establishing its chiral Z)2-structure 53). Similarity, the naphthaleno-phane 27b could be resolved by chromatography on silicagel coated with (—)-TAPA 49) and recently also by HPLC on optically active poly(triphenylmethyl methacrylate)49a) which also proved to be very useful for the optical resolution of many other axial and planarchiral aromatic compounds 49b>. 

Okamoto, Y., Honda, S., Hatada, K., and Yuki, H., IX. High-performance liquid chromatographic resolution of enantiomers on optically active poly(tri-phenylmethyl methacrylate), J. Chromatogr., 350, 127, 1985. 

Optically active poly(silyl ether)s were also synthesized by asymmetric induction on the silicon atom from chiral diols or a chiral Rh catalyst [178]. In the dehydrogenative polycondensations of bis(silane)s and several chiral diols, the highest ee value of the silicon atom was 13.7%. In the polymerization of a bis(silane) and an achiral diol, however, the use of only 5 mol% of RhCl[(R)-BINAP] resulted in induction of 39.8% ee of the silicon atom (Scheme 45). 

Figure 2 shows the UV absorption spectra of four optically active poly (dialkylsilane)s bearing different chiral side groups in THF at 30 °C [45]. It is evident that as the value of a increases from 0.59 to 1.25, the UV absorption intensity increases, whereas the full width at half maximum (fwhm) decreases. These results led to the finding of the semi-empirical relationship between the main chain absorption characteristics and the global conformation of various polysilanes in solution. 

Optically active poly(n-decyl-(S)-2-methylbutylsilane) (10) with an almost pure P-7 helix, optically inactive poly(n-decyl-i-pentylsilane) (32), and op-... 

Optically active poly(Y-ketosulfidc)s, similarly obtained from chiral bis-thiols, have also been studied.-" - ... 

The asymmetric oxidation reaction of prochiral poly(ester 0-sulfide)s to optically active poly(ester 0-sulfoxide)s can be accomplished with almost theoretical chemoselactivity and moderate to high enantioselectivity degrees. While the asymmetric oxidation of prochiral sulfides should not be a preparative method for chiral sulfoxides, we expect that the structure of the parent polymers might be specifically designed for the preparation of chiral thermotropic poly(ester 0-sulfoxi-de)s. 

The first optically active poly(isocyanide)s devoid of chiral groups on the nitrogen atom were isolated by optical resolution via column chromatography on the chiral stationary phase [44, 45]. Right- and left-handed helices of poly(fcrf-butyl isocyanide) (( )-30) (degree of polymerization ca. 20), which was prepared as a racemate by nickel-catalyzed polymerization, were successfully resolved on poly((S)- or (R)-sec-butyl isocyanide), which served as a chiral support for column chromatography (Scheme 27). Using poly((S)-... 

Okamoto, Y., Yuki, H. Resolution by Optically Active Poly(triphenylmethyl-methacrylate) in Asymmetric Reactions and Processes in Chemistry (E. L. Eliel, S. Otsuka, Eds.), ACS Symp. Series 185, 1982 ... 

A new type of enantioselective diene polymerization is found with cyclopolymerization of 1,5-hexadiene which leads to polymers with a saturated chiral main chain28,58>109. As catalyst, (—)-(7 )-[l,T-ethylenebis(4,5,6,7-tetrahydro-l-indenyl)]zirconium (/ )-binaphtholate is used in the presence of methylalumoxane to give optically active poly(methylene-1,3-cyclopentane) (3) with 68% trans configuration in the five-membered ring (diisotacticity). If the (S)-enantiomer of the ansa-metallocene with (ft)-binaphthol is used as catalyst then the opposite rotation of the polymer is observed58. 

B. Philip, K. Sreekumar, Optically active poly(ester-amide)s synthesis and charactmzation, Polym. Int. 50 (2001) 1318-1323. 

Faghihi K, Moghanian H. Synthesis and characterization of new optically active poly (amide-imide)s containing 1,3,4-oxadiazole moiety in the main chain. Polym Bull 2010 65(4) 319-32. 

Mallakpour S, Zadehnazari A. Synthesis and characterization of novel heat stable and pro-cessable optically active poly(amide-imide) nanostructures bearing hydroxyl pendant group in an ionic green medium. J Polym Environ 2013 21(1) 132. ... 

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